This invention relates to a metal cutting machine with a scrap saving feature.
The invention is directed primarily to machines for repetitive cutting of a plurality of small identical parts from a large flat metal plate, utilizing tracer controlled flame, plasma or laser cutting heads and the like. A scanning head is positioned above a template which is mounted to a tracing table. The scanning head is connected to drive one or a plurality of cutting heads and their supporting carriage to thereby cut a first series of one or more identically shaped parts from the plate-like workpiece.
When a first series of parts have been cut, it is desirable to cut a second and possibly more series of one or more parts from the same large workpiece. Heretofore this has been accomplished manually by the operator. Since the tracing table has previously been mounted for free movement transverse to the cutter carriage, the operator has manually shifted the table until, according to his visual observation, the lead-in indicia of the template was in a vertical plane parallel to the carriage and which passed through the workpiece just behind the previously cut-out portions. When the scanning head was moved to directly above this re-positioned indicia and the machine actuated, a second series of one or more parts was then cut out directly behind the first series.
The problem with the above-described operation has been that by depending on visual "eyeballing" to line up the template with the uncut portion of the workpiece, inaccuracies have often been found to occur. Thus, the operator did not always shift the tracing table and template far enough, the result being that the second series of cuts broke into the previously cut-out plate portions. Or, the operator may have shifted the table the template too far, leaving a large amount of workpiece unused. In the first case, the second series of one or more pieces was not fully formed and was completely wasted. In the second case, the workpiece was not utilized to its fullest. In both cases, a large amount of undesirable scrap resulted, thus increasing the cost of the operation.